A Decade of Cooling in Monterey and Humboldt Bays

Scientists to Look at Effects on Fish Populations

Researchers:

Larry Breaker
Moss Landing Marine Laboratories

Rick Starr
Moss Landing Marine Laboratories

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Revised:

October 5, 2010

Contact: Christina S. Johnson, csjohnson@ucsd.edu, 858-822-5334

MOSS LANDING – If you think global warming means its getting warmer everywhere, think again.

In Monterey and Humboldt bays, sea surface temperatures have dropped about one degree Celsius in the last decade.

The cooling is not a blip, says physical oceanographer Larry Breaker of Moss Landing Marine Laboratories, but an apparent trend since 2000. (See Figures 1 and 2.)

Figures 1 and 2. (Click on figures to view larger images.)

The sea surface temperature record at Dock B in Humboldt Bay and Pacific Grove in Monterey Bay shows seasonal variations in temperature superimposed on an overall cooling trend since 2000. L. Breaker/MLML

“The million dollar question is: Why is this happening?” he says.

The leading theory, now being explored, is that hotter days inland, in the Central Valley and Imperial Valley, are intensifying the atmospheric pressure gradient that drives upwelling friendly winds.

Upwelling of cold water from depth causes overcast conditions along the coast (aka, May gray and June gloom), and cooler surface waters (ask any surfer).

With Sea Grant support, Breaker is now examining whether the cooling can be directly linked to intensified upwelling during the same period. He is especially interested in tracking the path of upwelled water to see if it indeed enters the bays.

He will also document the extent of cooling offshore, as anecdotally fishermen have reported catching more warm-water species far from the coast.

Theoretically, cooling should lead to a decrease in the numbers of southern fish species.

“We don't know if this is occurring,” says MLML biologist Rick Starr, a collaborator on the project and also the interim director of the California Sea Grant Extension Program. He and his graduate student will soon begin mining landings data, scuba surveys and sportfishing tournament records to investigate whether there have indeed been climate-related shifts in fish populations in Monterey Bay.

“We are looking to learn whether the cooling is part of paradigm shift or a paradox,” Starr explains.